Lubrication system for a powertrain

ABSTRACT

The engine/transmission assembly includes a first chamber, a second chamber, and a fill hole that fluidly communicates with the first chamber. The first chamber is capable of containing lubricant at a first level, and the second chamber is capable of containing lubricant at a second level. The engine/transmission assembly also includes an opening that is between the first and second chamber and that fluidly communicates with the first and second chamber. The opening is positioned to maintain the first level in the first chamber and raise the second level in the second chamber when lubricant is added to the first chamber through the fill hole, and to maintain these two levels when the engine is running.

[0001] This application claims the benefit of prior filed co-pending provisional patent application No. 60/351,806 filed on Oct. 26, 2001.

[0002] FIELD OF THE INVENTION

[0003] The invention relates to powertrains including an engine and a transmission, and more particularly to lubrication systems for powertrains.

BACKGROUND OF THE INVENTION

[0004] Known powertrains generally include a crankshaft chamber that contains a crankshaft and a clutch chamber that contains a clutch assembly. The crankshaft chamber and the clutch chamber are either totally separate compartments or compartments that allow fluid communication of the lubricant.

[0005] Totally separate chambers include separate fill holes used to introduce lubricant into each of the separate chambers and separate dipsticks used to measure the amount of lubricant within each of the separate chambers. Powertrains that contain separate chambers are disadvantageous because multiple fill holes and dipsticks increase manufacturing costs and require the operator to check and fill multiple chambers thereby increasing maintenance time and expense.

[0006] Known fluidly connected chambers include holes that are positioned between the chambers to maintain the common lubricant at the same level in each chamber. These types of engines are disadvantageous because the level of the lubricant in the crankshaft chamber should be maintained below the crankshaft for efficient operation, however this level is inadequate to provide sufficient lubrication for the clutch assembly in the clutch chamber.

SUMMARY OF THE INVENTION

[0007] The engine/transmission assembly or powertrain of the present invention efficiently operates the crankshaft above the level of the lubricant in the crankshaft chamber and sufficiently lubricates the clutch assembly in the clutch chamber by positioning an overflow opening between the crankshaft chamber and the clutch chamber to maintain the level of lubricant in the clutch chamber at a level that is above the level of the lubricant in the crankshaft chamber.

[0008] The lubrication system decreases the manufacturing costs of the engine/transmission assembly and reduces the maintenance time required to maintain the proper fill level of lubricant by eliminating the need for separate lubricant fill holes and dipsticks. The proper fill level is obtained by measuring the fill level of the lubricant in the crankshaft chamber and by supplying lubricant to the clutch chamber through a single fill hole.

[0009] One embodiment of the present invention is directed to an engine/transmission assembly that includes a first chamber, a second chamber, and a fill hole that fluidly communicates with the first chamber. The first chamber is capable of containing lubricant at a first level, and the second chamber is capable of containing lubricant at a second level. The engine/transmission assembly also includes an opening that is between the first and second chamber and that fluidly communicates with the first and second chamber. The opening is positioned to maintain the first level in the first chamber and raise the second level in the second chamber when lubricant is added to the first chamber through the fill hole.

[0010] Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a side view illustrating an engine/transmission assembly embodying the present invention.

[0012]FIG. 2 is a partial cross section view taken along line 2-2 in FIG. 1, illustrating a chain tower of the engine/transmission assembly.

[0013]FIG. 3 is a cross section view taken along line 3-3 in FIG. 2, illustrating a clutch chamber of the engine/transmission assembly.

[0014]FIG. 4 is a partial cross section view taken along line 4-4 in FIG. 1, illustrating an overflow opening and a dipstick of the engine/transmission assembly.

[0015]FIG. 5 is a partial cross section view taken along line 5-5 in FIG. 1, illustrating a drain hole of the engine/transmission assembly.

[0016]FIG. 6 is a partial cross section view taken along line 6-6 in FIG. 1, illustrating a fill hole of the engine/transmission assembly.

[0017]FIG. 7 is a schematic view illustrating the operation of the engine/transmission assembly shown in FIG. 1.

[0018] Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order.

DETAILED DESCRIPTION

[0019]FIG. 1 illustrates an engine/transmission assembly 10 of the present invention. The engine/transmission assembly 10 includes a housing 12 and an engine 14 including a cylinder housing 16, a cylinder head 18, and a cylinder head cover 20.

[0020] In further reference to FIG. 4, the housing 12 includes a first side 24 that includes an outboard wall 26 and a curved outer wall 28 that extends from the perimeter of the outboard wall 26 and that is substantially perpendicular to the outboard wall 26. A forward portion 30 of the outer wall 28 is configured to partially define a cylinder bore 32 (FIG. 2). The first side 24 also includes a lubricant filter cavity 34 that houses a lubricant filter 35 (shown schematically in FIG. 7) which is capable of removing contaminates from a lubricant 36.

[0021] The housing 12 also includes a second side 38 that includes an outer wall 40. A forward portion 42 of the outer wall 40 is configured to partially define the cylinder bore 32 (FIG. 2), and the outer wall 40 includes a chain cavity 44 (FIGS. 2 and 3).

[0022] The second side 38 also includes a dividing wall 46 that extends approximately perpendicularly from the outer wall 40 and that divides the outer wall 40 into first and second portions 48, 50. The dividing wall 46 includes an overflow opening 52, and the second portion 50 of the outer wall 40 includes a drain hole 54 that is capable of draining a lubricant 36 (FIG. 5).

[0023] The housing 12 also includes a second side cover 56 that has an outboard wall 58 and an outer wall 60 that extends from the perimeter of the outboard wall 58 and that is substantially perpendicular to the outboard wall 58. As shown in FIG. 6, the outboard wall 58 also includes a lubricant fill hole 62 that opens substantially upwardly to allow a lubricant 36 to be poured into the lubricant fill hole 62. The lubricant fill hole 62 includes internal threads 64 to threadingly engage with external threads 66 on an lubricant fill hole cap 68. The outboard wall 58 also includes a projection, or sight blocker 70 that extends from the outboard wall 58. The sight blocker 70 is positioned below the lubricant fill hole 62 and above lubricant level 198 to obstruct the view of the lubricant level 198 through the fill hole 62.

[0024] The configuration of the housing 12 is not limited to the illustrated embodiment and can vary without departing from the scope of the present invention.

[0025] Referring back to FIG. 4, the outboard wall 58 also includes a dipstick housing 72 that extends toward the bottom of the outboard wall 58 and into the outer wall 60 of the second side cover 56. The dipstick housing 72 includes internal threads 74 that threadingly engage external threads 76 of a dipstick 78 that extends through a substantial portion of the dipstick housing 72.

[0026] With specific reference to FIGS. 4 and 5, the second side 38 and the second side cover 56 are fastened together such that a gasket (not shown) is coupled between an adjacent face 80 of the outer wall 60 of the second side cover 56 and an adjacent face 82 of the first portion 48 of the outer wall 40 of the second side 38 to form a first, or clutch chamber 84. The clutch chamber 84 is defined by the outboard wall 58 of the second side cover 56, the dividing wall 46, the first portion 48, and the outer wall 60 of the second side cover 56. The clutch chamber 84 is in fluid flow communication with the drain hole 54, the fill hole 62, the overflow opening 52, and the chain cavity 44.

[0027] The first side 24 and the second side 38 are fastened together such that a gasket (not shown) is coupled between an adjacent face 86 of the outer wall 28 of the first side 24 and an adjacent face 88 of the second portion 50 of the outer wall 40 of the second side 38 to form a second, or crankshaft chamber 90. The crankshaft chamber 90 is defined by the outboard wall 26 of the first side 24, the dividing wall 46, the second portion 50, and the outer wall 28 of the first side 24. The crankshaft chamber 90 is in fluid flow communication with the drain hole 54, the overflow opening 52, the cylinder bore 32, and the dipstick housing 72 through a passageway 91 that is positioned in the first portion 48 of the outer wall 40 of the second side 38 and adjacent to the clutch cavity. The drain hole 54 includes internal threads 92 that are removably threadingly engaged with external threads 94 on a drain plug 96. When the drain plug 96 is inserted into the drain hole 54 the drain plug 96 blocks the clutch and crankshaft chamber 84, 90 from being fluidly connected with each other and with the drain hole 54.

[0028] Referring to FIG. 2, the cylinder housing 16 includes the cylinder bore 32, cooling fins 102, and the chain cavity 44. The cylinder bore 32 extends through the cylinder housing 16 along a bore axis 106, and the cooling fins 102 extend perpendicularly from the bore axis 106 from top, bottom, and side faces 108, 110, 112 of the cylinder housing 16 (FIG. 1).

[0029] The cylinder head 18 includes a cam shaft 116, rocker arms (not shown), intake and exhaust valves (not shown), and a spark plug 124. The cam shaft 116 is rotatably mounted to the cylinder head 18 and includes first and second lobes 128. The cam shaft 116 includes a cam sprocket 130 that is positioned within the chain cavity 44 of the cylinder head 18 and that engages a chain 134. The rocker arms are pivotably connected to a rocker shaft (not shown) and slidably engage the lobes 128 of the cam shaft 116. The valves include stems that engage the rocker arms and valve heads 138 that are biased against valve seats in the cylinder head 18. The cylinder head 18 is connected to the cylinder housing 16 such that the valve heads 138 and the spark plug 124 communicate with a combustion chamber 142 of the cylinder bore 32.

[0030] The cylinder head cover 20 is connected over the cylinder head 18 for protection and to prevent the lubricant 36 from escaping the engine/transmission assembly 10. The cylinder head cover 20, the cylinder head 18, the cylinder housing 16, and the housing 12 are connected with elongated bolts (not shown) that extend from the housing 12 through holes (not shown) located in the corners of the cylinder housing 16, the cylinder head 18, and the cylinder head cover 20.

[0031] The engine/transmission assembly 10 as illustrated in FIGS. 4-6 includes a crankshaft 144, a clutch assembly 146, an intermediate shaft 148, and an output shaft 150. As shown in FIG. 5, the crankshaft 144 is rotatably coupled between the outboard wall 26 of the first side 24 and the dividing wall 46 of the second side 38. The crankshaft 144 is substantially positioned within the crankshaft chamber 90 and includes a crankshaft axis 152. The crankshaft 144 includes a crank pin 154 that is offset from the crankshaft axis 152. A connecting rod 158 rotatably connects the crank pin 154 with a piston 160 that is positioned for reciprocal motion in the cylinder bore 32 to rotate the crankshaft 144 (FIG. 2). The crankshaft 144 also includes at one end a pump drive gear 162 that drives a pump 163 (shown schematically in FIG. 7) that distributes lubricant 36 throughout the engine. The other end of the crankshaft 144 extends through the dividing wall 46 and into the clutch chamber 84 where it couples to the clutch assembly 146 and a drive sprocket 164 that drives the chain 134 which engages to the cam sprocket 130.

[0032] The clutch assembly 146 includes an automatic clutch 166 that is connected to the crankshaft 144 and that is rotatably coupled to the outboard wall 58 of the second side cover 56. The automatic clutch 166 is positioned within the clutch chamber 84.

[0033] Referring again to FIG. 4, the intermediate shaft 148 is rotatably coupled to the outboard wall 58 of the second side cover 56 and the outboard wall 26 of the first side 24. The intermediate shaft 148 extends through the overflow opening 52. The intermediate shaft 148 includes a first portion 172 positioned within the clutch chamber 84 and a second portion 174 positioned within the crankshaft chamber 90. The first portion 172 engages the clutch assembly 146 and the second portion engages the output shaft 150.

[0034] As shown in FIG. 6, the output shaft 150 is rotatably coupled to the dividing wall 46 of the second side 38 and the outboard wall 26 of the first side 24. The output shaft 150 extends through the outboard wall 26 of the first side 24 and is coupled to an output sprocket 184 that can engage a drive chain 186 which could be used to rotate a wheel of a scooter, for example.

[0035] Prior to running the engine, the clutch chamber 84 and the crankshaft chamber 90 are filled with a lubricant 36 that is used along with a lubrication system 196 (shown schematically in FIG. 7) to lubricate the components of the engine/transmission assembly 10. Initially, the lubricant fill hole cap 68 is removed and the lubricant 36 is poured into the clutch chamber 84 through the open fill hole 62. After the clutch chamber 84 is filled up to the level of the overflow opening 52, the excess lubricant 36 will run through the overflow opening 52 and into the crankshaft chamber 90 to begin filling the crankshaft chamber 90. The sight blocker 70 prevents the operator from seeing the fill level of the clutch chamber 84 to ensure that the operator uses the dipstick 78 to measure the fill level of the lubricant 36. If the sight blocker 70 was not present, an operator might incorrectly conclude that both chambers 84, 90 are properly filled based on visually confirming that the clutch chamber 84 is filled.

[0036] The operator uses the dipstick 78 to determine the level of lubricant 36 in the crankshaft chamber 90 and adds lubricant 36 to the clutch chamber 84 until the level in the crankshaft chamber 90 is properly within the limits marked on the dipstick 78. When the lubricant 36 in the crankshaft chamber 90 is within the limits of the dipstick 78, the lubricant 36 is at the proper fill level. At the proper fill level, the lubricant 36 in the clutch chamber 84 is at the first lubricant level 198 such that the automatic clutch 166 is partially submerged in the lubricant 36, and the lubricant 36 in the crankshaft chamber 90 is at a second level 200 such that the crankshaft 144 is positioned substantially above the lubricant 36 throughout the rotation of the crankshaft 144. After the proper fill level is obtained, the lubricant fill cap 68 and dipstick 78 are replaced. The proper fill level as shown in the drawings and as mentioned in the specification and claims is measured when the engine 14 is at rest.

[0037] The operation of the lubrication system 196 is described with reference to FIG. 7. The pump 163, which is driven by the pump drive gear 162 of the crankshaft 144, pumps lubricant 36 from the crankshaft chamber 90 and moves the lubricant 36 to the lubricant filter 35 within the lubricant filter cavity 34. From the lubricant filter cavity 34 the flow of lubricant 36 is split into a first portion 202 that is diverted to the crankshaft 144 and a second larger portion that is diverted to the cylinder head 18.

[0038] The first portion 202 moves through the outboard wall 26 of the first side 24 to lubricate a bearing 206 of the crankshaft 144 and moves through a hollow passage of the crankshaft 144 to lubricate between the crank pin 154 and connecting rod 158. The lubricant 36 then exits the bearing 206 and the crank pin 154 and falls to accumulate in the crankshaft chamber 90.

[0039] In further reference to FIG. 7, the second portion 204 of lubricant 36 moves up through the cylinder housing 16 and the cylinder head 18 by flowing through a clearance between a bolt and bolt hole. Once the second portion 204 of lubricant 36 reaches the cylinder head 18, the lubricant 36 escapes the hole to lubricate a first cam bearing 208 (FIG. 2). The lubricant 36 then enters into a passageway in the rocker shaft to intermittently lubricate the rocker arms and cam lobes 128. The lubricant 36 escapes through holes in the rocker shaft and holes in the rocker arms that align when the rocker arms are in a specific position relative to the rocker shaft. The remaining lubricant 36 in the rocker shaft flows across the rocker shaft to lubricate the second cam bearing (not shown).

[0040] After the second portion 204 of lubricant 36 is diverted throughout the cylinder head 18, it collects in the cam/rocker arm cavity until it overflows into the chain cavity 44 of the cylinder head 18 and down the chain cavity 44 into the clutch chamber 84 (FIG. 3). The clutch chamber 84 will feed excess lubricant 36 into the crankshaft chamber 90 through the overflow opening 52, and the lubricant 36 will therefore be maintained at the proper levels in the clutch and crankshaft chambers 84, 90.

[0041] Since the overflow opening 52 regulates a constant lubricant level 198 in the clutch chamber 84, consumed lubricant will affect the lubricant level 200 only in the crankcase chamber 90 where it can be measured by dipstick 78.

[0042] The invention is not limited to the illustrated powertrain. Different clutch assemblies, valve trains, and lubrication paths can be used without departing from the scope of the present invention. 

We claim:
 1. An engine/transmission assembly comprising: a first chamber capable of containing lubricant at a first level when the engine/transmission assembly is at rest; a second chamber capable of containing lubricant at a second level when the engine/transmission assembly is at rest; a fill hole fluidly communicating with the first chamber; and an opening in fluid communication between the first chamber and the second chamber, the opening being positioned to substantially maintain the first level in the first chamber when the engine is at rest and raise the lubricant in the second chamber when lubricant is added to the first chamber through the fill hole.
 2. The engine/transmission assembly of claim 1, wherein each chamber has a bottom, the engine/transmission assembly further comprising a drain hole fluidly communicating with the bottom of the first chamber and the bottom of the second chamber, the drain hole being capable of allowing lubricant to drain from the first and second chambers.
 3. The engine/transmission assembly of claim 2, further comprising a drain plug insertable into the drain hole and capable of preventing fluid communication between the first and second chamber through the drain hole.
 4. The engine/transmission assembly of claim 1, further comprising a housing that includes a first side, a second side, a bottom, and a wall that divides the first side from the second side, wherein the first chamber is partially defined by the first side, the wall, and the bottom, and the second chamber is partially defined by the second side, the wall, and the bottom.
 5. The engine/transmission assembly of claim 4, wherein the wall separates the first chamber from the second chamber.
 6. The engine/transmission assembly of claim 5, wherein the opening is in the wall.
 7. The engine/transmission assembly of claim 1, further comprising a clutch assembly positioned within the first chamber.
 8. The engine/transmission assembly of claim 7, further comprising a crankshaft connected to the clutch assembly and substantially positioned within the second chamber.
 9. The engine/transmission assembly of claim 8, wherein the clutch assembly is a least partially positioned below the opening.
 10. The engine/transmission assembly of claim 9, wherein the opening is positioned to maintain the first level such that the clutch assembly is at least partially below the first level in the first chamber and maintaining the second level such that the crankshaft is entirely positioned above the second level of the second chamber.
 11. The engine/transmission assembly of claim 8, further comprising an output shaft substantially positioned within the second chamber and an intermediate shaft coupled to the clutch assembly in the first chamber and coupled to the output shaft in the second chamber, the intermediate shaft extending through the opening.
 12. The engine/transmission assembly of claim 1, further comprising a projection extending into the first chamber, wherein the projection is positioned below the fill hole, the projection capable of making the first level of the first chamber substantially visually inaccessible from the outside of the first chamber through the fill hole.
 13. The engine/transmission assembly of claim 1, further comprising a dipstick capable of measuring the second level of the second chamber.
 14. The engine/transmission assembly of claim 13, wherein the engine/transmission assembly includes exactly one dipstick.
 15. The engine/transmission assembly of claim 13, further comprising a passageway fluidly connecting with the second chamber, wherein the passageway extends adjacent to the first chamber, the dipstick being insertable into the passageway and removable from the passageway.
 16. The engine/transmission assembly of claim 1, further comprising a pump capable of removing lubricant from the second chamber, and distributing the lubricant throughout the engine such that at least some of the lubricant returns to the first chamber.
 17. The engine/transmission assembly of claim 1, wherein the engine/transmission assembly includes exactly one fill hole for lubricant.
 18. A method of lubricating an engine/transmission assembly having moving parts, the method comprising: providing a first chamber containing clutch components; providing a second chamber having a crankshaft; providing a regulator opening between the first and second chambers; drawing a lubricant from the second chamber to lubricate the moving parts; returning at least some of the lubricant used to lubricate the moving parts to the first chamber; regulating a lubricant level in the first chamber using the regulator opening by overflowing lubricant from the first chamber to the second chamber when the lubricant level in the first chamber reaches a first level.
 19. The method of claim 18, further comprising: filling the first chamber to the first level with the lubricant through a fill hole; and filling the second chamber to a second level by overflowing lubricant from the first chamber to the second chamber through the regulator opening.
 20. The method of claim 19, further comprising: measuring the level of the lubricant in the second chamber with a dipstick.
 21. The method of claim 18, further comprising: rotating the clutch components at least partially below the first level.
 22. The method of claim 18, further comprising: rotating the crankshaft above the level of the lubricant in the second chamber.
 23. The method of claim 18, further comprising: removing a drain plug to drain the lubricant from the first and second chambers. 